1. The Field of the Invention
This invention relates to novel benzaldehydes having a silver halide developing capability and which are particularly useful as intermediates for the preparation of yellow azo methine dyes having particularly desirable performance characteristics in photographic products and processes.
2. Description of the Prior Art
Yellow dyes having a silver halide developing capability, e.g., a silver halide developing substituent are known to the art. Such dyes, commonly referred to as "dye developers", are disclosed in the following U.S. Pat. Nos.: 3,134,672; 3,134,764: 3,135,604; 3,135,734; 3,141,772; 3,183,090; 3,309,199; 3,424,742; 3,597,200; 3,705,184 and 3,752,836.
Of the above Patents, U.S. Pat. Nos. 3,597,200; 3,705,184 and 3,752,836 particularly relate to yellow dye developers having azomethine dyes chrome complexed to a substantially colorless ligand which provides the substituent having the silver halide developing capability. The yellow azomethine dyes of these Patents are of the following general formula: ##STR2## where the alkoxy moiety contains 1-8 carbon atoms and n and m each are the integers 1 or 2.
As described in these Patents and particularly in U.S. Pat. No. 3,705,184, the yellow ortho, ortho' dihydroxy azomethine dyes of Formula 1 can be prepared by reacting an alkoxy-substituted o-hydroxybenzaldehyde with a nitro-substituted o-hydroxyaniline according to the following reaction scheme: ##STR3##
As also disclosed in these Patents, the yellow ortho, ortho' dihydroxy azomethine dyes of Formula 1 can be chrome-complexed with a substantially colorless ligand to provide 1:1 chrome-complexed yellow dye developers. The particularly preferred 1:1 chrome complexed yellow dye developers are those of the following general formula: ##STR4## where, m and n are 1 or 2, (alkoxy) has from 1-8 carbon atoms and --alkylene-- has from 1-6 carbon atoms.
1:1 chrome complexed yellow azomethine dyes of the above Formula 2 have excellent performance characteristics in terms of color as well as stability. In fact, a chrome complexed azomethine of Formula 2 which conforms to the following specific formula has enjoyed extensive success in commercial diffusion transfer, photographic film units. ##STR5## With each --OC.sub.3 H.sub.7 being normal propanol.
This invention presents to the art novel benzaldehydes having a silver halide developing substituent. These novel benzaldehydes are valuable intermediates particularly useful in the preparation of yellow azomethine dyes having a silver halide developing capability and especially chrome complexed yellow azomethine dye developers having performance characteristics substantially equivalent to and in some respects, superior to yellow azomethine dye developers known to the art.